What would you do with 1,000 butts if you had them?
Ramisyllis multicaudata, a sea worm, is one of only two known creatures to find itself in this precarious predicament (shopping for trousers must be a nightmare)—and it isn’t telling.
Given that a worm doesn’t “just happen” to have that many booties, there must be a solid explanation, and recent anatomical research has provided some juicy hints.
The narrative begins in a typical manner.
Ramisyllis is a bristle worm that dwells in the water channels of a sponge named Petrosia off the coast of northern Australia.
Its solitary, unimpressive, and sluggish head is hidden deep within the sponge.
Things start to become strange after that.
Its body starts to branch out randomly.
The legion of posteriors that arise may emerge into the saltwater and amble around the sponge’s surface through natural pores.
Scientists discovered a “tiny” sponge containing more than 100 crawling worm fannies, often more than ten to a single hole.
Although sponges are many wonderful things, one of them is that they are not conscious, which must be considered a win in this case.
In addition, each branch has its internal organs.
These organs are identical to those of the unbranched juvenile, according to the first thorough anatomical examination of these worms, published this year in the Journal of Morphology by a team from Spain, Australia, and Germany.
They also discovered that the worm’s gut is continuous throughout the whole labyrinthine creature, but that it is glaringly empty.
There has never been any sponge tissue or food particles detected within.
The worm’s hind intestine, however, is coated with cilia and microvilli, little fingerlike extensions that increase the surface area accessible for food absorption (your gut is covered in a similar velvety lining of villi and microvilli).
That means their guts might still work, but it’s unclear how the vast creatures could survive on food that enters just through their severely insufficient regulation-sized mouth.
What fascinates me about these worms is that they look to be an animal that has taken up a fungal lifestyle.
If you look at a fungus under a microscope, you’ll notice a system of branching tubes that looks a lot like Ramisyllis.
And this resemblance raises the possibility of what these worms are up to in their sponges.
Fungi are scavengers who eat only what they need.
They burrow into their meal, produce digestive enzymes, and then resorb the slime that results.
Their highly branching, filamentous bodies emphasize surface area because, unlike humans, they do not have a lengthy gut squeezed into a small body.
Instead, their whole body is an intestine, from the inside out.
The more body you have, the more food you can eat in this scenario.
Soft-bodied marine invertebrates have long been known to absorb dissolved organic materials (a.k.a. liquid food) straight from saltwater via their “skin.”
Ramisyllis, on the other hand, appears to have gone this a step further, since the anatomy team observed that the worm’s body is also strangely coated with lengthy microvilli.
Given the Ramisyllis body plan’s great emphasis on square footage—and the absence of attention on developing heads or mouths that are appropriate for the situation—one must strongly believe that they, like fungi, have turned their outsides into insides.
Allow me to provide Exhibit B: their bizarre reproduction mechanism if their massively branched bodies aren’t enough to imply fungus.
The fact that Ramisyllis would never go on a date is the first indication of their unconventional existence.
You’ve committed to a home, not a relationship, once you’ve squeezed hundreds of tentaclelike branches into the water passageways of a Petrosia sponge (or even a hookup).
The typical remedy is to toss your millions of cheap gametes into the sea, wave goodbye, and turn on some must-see television.
Corals and sea anemones are two examples of this enviable reproduction technique.
However, Ramisyllis and many other syllid polychaete worms did not take this path.
A little tail called a pygidium sits at the rear of their bodies (trilobites also had this cute butt flap).
The polychate worm equivalent of the apical meristem in plants is just in front of it: the posterior growth zone, where stem cells continually create new body parts.
These are used by polychaete worms to create new segments.
However, this is a unique condition for animals, and it has resulted in some unique outcomes.
Instead of forming a new standard segment, these areas may begin to construct a head with a primitive brain and four eyes.
Following the head are other body pieces filled with gametes, and before you know it, the mother ship has a sexy little hot rod connected to it, ready to be ejected when the time comes.
These clones (botanically referred to as “stolons”; strawberry runners and other horizontal plant stems are sometimes referred to as “stolons”) are equipped with paddles, driving directions, and a libido.
In a nutshell, Ramisyllis creates autonomous gonads that fall between a detached penis and a college freshman.
The syllids, to which these worms belong, are possibly unique among bilaterally symmetrical creatures in their unusual reproduction method, which is known as “gemmiparous schizogamy.”
Of course, certain insects generate transitory adults whose primary purpose is to bang extremely tiny, highly urgent boots, but they typically survive as larvae for a considerably longer length of time.
They also don’t sprout from existing insects.
That’s a mycological approach to taking care of things.
Indeed, pictures of the fungus Fusarium with its unique boat-shaped spores seem very similar to photographs of a Ramisyllis stolon amidst the branches of its generative worm.
Other nonbranching syllid species’ stolons, like fungal spores, can be produced in bunches or chains.
It’s possible that syllid worms developed multiple-choice bodies as a result of their reproductive habits.
Making a branch with a sex-seeking clone may be as simple as replacing the ordinary parts with sex-seeking clones.
Nonetheless, something about this narrative irritates me.
Why is there such a focus on all the many backsides reaching the sponge’s surface if their entire bodies can absorb dissolved food?
Bunches of worm butts were discovered tucked inside sponge cul-de-sacs in one specimen examined by scientists.
The scientists determined that this was due to the backsides’ failed effort to reach the surface.
The tails also contain an unidentified brilliant white pigment that they produce whether or not they reach the topside.
Why is it so critical that the tails find a way out?
Is the dissolved organic stuff outside the sponge that much better?
What’s more, why are they donning the equivalent of highway reflective paint?
Is it just to apply sunscreen?
Is there another purpose for it?
Even while Ramisyllis appears to be doing what I would do with a thousand booties—shake them—it is unclear exactly what it is doing with them.
the author is Jennifer Frazer, an AAAS Science Journalism Award–winning science writer, authored The Artful Amoeba blog for Scientific American. She has degrees in biology, plant pathology and science writing.